Synthesis of pyrazolo[1,2-a]pyrazole-based peptide mimetics

Novak, Ana; Testen, Ana; Bezenšek, Jure; Grošelj, Uroš; Hrast, Martina; Kasunič, Marta; Gobec, Stanislav; Stanovnik, B.; Svete, Jurij

doi:10.1016/j.tet.2013.05.122

Cited by 18 publications

(21 citation statements)

References 43 publications

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“…Under slightly elevated pressure (3 bar), the amine 37 and CO 2 are in equilibrium with the carbamic acid 38, which cyclizes to N-amino hydantoin 39. 40 The proposed mechanism is supported by known, closely related examples of cyclizations of N-benzyloxycarbonyl-α-amino acid hydrazides [55][56][57] and α-semicarbazidoacetates [58][59][60] into 3-aminoimidazolidine-2,4-diones. Besides, the above transformation is also related to Bucherer's synthesis of hydantoins, which proceeds in a closed vessel under slightly elevated pressure utilizing CO 2 (or carbonate) as a C 1 -synthon (Scheme 9).…”

Section: Figure 2 Functionalizations Of Ring Nitrogen Atoms With Elementioning

confidence: 85%

“…. 41 Having this small, stereochemically diverse library of dipeptides 43-49 in our hands, we continued with selective deprotection of the amino and the carboxy function. Acidolytic deprotection of the carboxy group afforded the corresponding carboxylic acids 50a-e in 67-100% yields, while hydrogenolytic deprotection of the amino group afforded the corresponding free amines 51a-d in 20-94% yields (Scheme 15).…”

Section: Page 189mentioning

confidence: 99%

“…in refluxing anisole. 9 Somewhat expectedly, 40 reactions of 5-phenyl substituted dipoles 24a,b furnished, along with cycloadducts 43-46, the hydantoin derivatives 35a,b in ~25% yields. Evaporation of the filtrates followed by separation by column chromatography (CC) and medium pressure liquid chromatography (MPLC) then furnished the corresponding cycloadducts 43a-45a, 44b, and 46b in 5-36% yields (Scheme 12).…”

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confidence: 98%

“…with α-amino acid derivative), followed by separation of the so formed diastereomers would give non-racemic tripeptides. 41 The starting 3-pyrazolidinones 4 and azomethine imines 24 were prepared as described previously (cf. Schemes 1 and 6).…”

mentioning

confidence: 99%

“…Schemes 1 and 6). [40][41][42] First, cycloadditions of 5-phenyl substituted dipoles 24a,b to tert-butyl acrylate were carried out under standard conditions, i.e. in refluxing anisole.…”

mentioning

confidence: 99%

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Recent advances in the synthesis of polysubstituted 3-pyrazolidinones

Grošelj¹,

Svete²

2015

Arkivoc

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An account of recent developments in the field of 3-pyrazolidinone chemistry is given with special focus on the synthesis and transformations of 5-substituted 4-benzyloxycarbonylamino-3-pyrazolidinones, pyrazolo[1,2-a]pyrazole-based peptide analogues, and tetrahydropyrazolo-[1,5-c]pyrimidine-2,7-diones. In terms of practical application, polyfunctionalized 3-pyrazolidinones as 'aza-deoxa' analogues of cycloserine, peptide mimetics based on 3-amino-2-oxo-1,5-diazabicyclo[3.3.0]octane-7-carboxylic acid, and 1,6-disubstituted tetrahydropyrazolo[1,5-c]-pyrimidine-2,7-diones as the first representatives of a novel saturated heterocyclic system were prepared by these newly developed synthetic methods.

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Section: Figure 2 Functionalizations Of Ring Nitrogen Atoms With Elementioning

confidence: 85%

Section: Page 189mentioning

confidence: 99%

mentioning

confidence: 98%

mentioning

confidence: 99%

“…Schemes 1 and 6). [40][41][42] First, cycloadditions of 5-phenyl substituted dipoles 24a,b to tert-butyl acrylate were carried out under standard conditions, i.e. in refluxing anisole.…”

mentioning

confidence: 99%

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Recent advances in the synthesis of polysubstituted 3-pyrazolidinones

Grošelj¹,

Svete²

2015

Arkivoc

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[3 + 2] Cycloadditions of Azomethine Imines

Grošelj

Svete

2020

Organic Reactions

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In spite of their late discovery in the middle of 20 th century, the importance of azomethine imines and their [3+2] cycloaddition reactions has grown constantly throughout the decades. Today, [3+2] cycloadditions of azomethine imines have become indispensable in the preparation of pyrazole derivatives with all degrees of saturation. The structural diversity of azomethine imines is wide and comprises acyclic, C , N ‐cyclic, N , N ‐cyclic, and C , N , N ‐cyclic 1,3‐dipoles. Although electron‐deficient dipolarophiles are preferred, electron‐rich dipolarophiles, such as enol ethers and enamines, are also commonly used in these reactions. Compared to cyclocondensation methods and [3+2] cycloadditions with diazoalkanes and nitrile imines, [3+2] cycloadditions with azomethine imines provide access to a greater diversity of pyrazole derivatives with all degrees of saturation. As with other 1,3‐dipolar cycloadditions, a concerted and nearly synchronous mechanism has been proposed for most [3+2] cycloadditions of azomethine imines, although a stepwise mechanism may be viable in some cases. Several examples of asymmetric [3+2] cycloadditions of azomethine imines that afford non‐racemic cycloadducts with high enantioselectivity have been reported. These asymmetric cycloadditions are performed with various types of transition metal catalysts and organocatalysts, and indicate their potential for the asymmetric synthesis of saturated pyrazole derivatives. Finally, many examples of copper‐catalyzed and thermal, strain‐promoted [3+2] cycloadditions of azomethine imines (in particular sydnones) clearly indicate wide applicability of these reactions in bioconjugation, fluorescent labelling, materials functionalization, and other applications outside the realm of pure organic synthesis.

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Desymmetrization of 1,4‐Pentadien‐3‐ol by the Asymmetric 1,3‐Dipolar Cycloaddition of Azomethine Imines

Yoshida

Sassa

Kato

et al. 2014

Chemistry A European J

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Desymmetrization of the divinyl carbinol, 1,4-pentadien-3-ol, was accomplished by the asymmetric 1,3-dipolar cycloaddition of azomethine imines based on a magnesium-mediated, multi-nucleating chiral reaction system utilizing diisopropyl (R,R)-tartrate as the chiral auxiliary. The corresponding optically active trans-pyrazolidines, each with three contiguous stereogenic centers, were obtained with excellent regio-, diastereo-, and enantioselectivity, with results as high as 99% ee. This reaction was shown to be applicable to both aryl-and aliphatic-substituted azomethine imines. The use of a catalytic amount of diisopropyl (R,R)-tartrate was also effective when accompanied by the addition of MgBr 2 .

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Synthesis of pyrazolo[1,2-a]pyrazole-based peptide mimetics

Cited by 18 publications

References 43 publications

Recent advances in the synthesis of polysubstituted 3-pyrazolidinones

Recent advances in the synthesis of polysubstituted 3-pyrazolidinones

[3 + 2] Cycloadditions of Azomethine Imines

Desymmetrization of 1,4‐Pentadien‐3‐ol by the Asymmetric 1,3‐Dipolar Cycloaddition of Azomethine Imines

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